This invention relates to a quantizer that can be used for providing a digital signal with a required number of bits. More specifically, the invention relates to a quantizer in which the quantisation interval can be adjusted.
In many cases, where digital signals are being processed in an electronic device, a digital signal is received with a certain number of bits representing each value of the signal. For example, in a wireless communications device, an analog signal is received, and this is converted to a digital signal by means of an analog-digital converter. The precision of the analog-digital converter determines how many bits represent each sample value. For example, each sample value may be represented by a 16 bit value.
Other signal processing blocks may work best with sample values being represented by particular numbers of bits. Where the number of bits in each initial sample value differs from the number of bits required per sample value for further processing of the received signal, it is necessary to use a quantizer to adjust the number of bits representing each sample value. Then, each received sample is allocated to one of a number of bins, with each bin corresponding to one of the possible quantizer output values.
In making this adjustment, one issue that must be considered is the dynamic range of the high resolution sample values. Where the signals received by the quantizer occupy a large proportion of the range of possible values, that is, the sample values have a large dynamic range, then each bin must be relatively wide, in order to ensure that the quantizer output values can properly distinguish between different sample values. Where the signals received by the quantizer occupy a smaller proportion of the range of possible values, each bin must be relatively narrow, in order to ensure that the quantizer output values can property distinguish between different sample values.